A 20-year-old male was referred to our hospital to undergo operative treatment due to aortic valve insufficiency which had gradually worsened. The patient's chief complaint was a loss of breath upon effort which had progressively worsened after undergoing aortic valve plasty (AVP) for aortic valve insufficiency with infective endocarditis at another institution. AVP by the cusp extension method had been performed because of the patient's youth and there had been no change in the morbid state, except for the presence of a non-coronary cusp. In addition, the aortic valve insufficiency was controlable and postoperative course was also excellent. The cusp extension method was therefore considered to be an appropriate procedure for this case since it would allow the patient to return it to a state with a more normal heart, since the valve organization after this procedure would be able to reach a maximum level.

Although the pressure gradient (PG) and the effective orifice area (EOA) have been used as indices of prosthetic valve function, these values show correctly neither energy loss, nor increased workload. This study aimed to evaluate the prosthetic valve function using echocardiography and PG, EOA and energy loss index, a new index advocated by Garcia et al. These were calculated for 40 patients with aortic prosthetic valve replacement by SJM valve (19HP, 6 cases; 21mm, 16 cases; 23mm, 14 cases; 25mm, 4 cases). Preoperative and postoperative echocardiographic measurements and their variations were analyzed and compared according to the size of implanted valve. In the comparison before and after aortic valve replacement, left ventricular mass (383±151g vs 288±113g, p<0.01), SV1+RV5 on ECG (5.07±1.73mV vs 3.83±1.5mV, p<0.01), and diastolic left ventricular posterior wall thickness (14.4±3.7mm vs 12.9±2.8mm, p<0.05) decreased significantly after the operation. However, there was no significant difference according to the size of the prosthetic valve in these reduction rates caluculated by (preoperative value-postoperative value)/preoperative value. Small size prosthetic valves were used for patients with small diameter of left ventricular outflow tract (LVOT) (19HP, 18±2mm; 21mm, 21±2mm; 23mm, 23±4mm; 25mm, 27±3mm; p<0.01) and small body surface area (19HP, 1.5±0.2m²; 21mm, 1.5±0.2m²; 23mm, 1.7±0.1m²; 25mm, 1.8±0.1m²; p<0.01) in our study. There was a signifcant difference in EOA (19HP, 1.2±0.4cm²; 21mm, 1.9±0.7cm²; 23mm, 2.2±0.9cm²; 25mm, 3.5±1.1cm²; p<0.01), but not in ELI (19HP, 1.01±0.41cm²/m²; 21mm, 1.87±1.03cm²/m²; 23mm, 1.83±1.09cm²/m²; 25mm, 3.08±1.21cm²/m²; p=0.055) according to the size of the prosthetic valve. Small size prosthetic valves had small EOA, but showed satisfactory valve function in decreasing left ventricular hypertrophy and reducing LVM and ELI of small size was similar to that of large size.

BACKGROUND: To develop human space exploration, it is necessary to study the effects of an isolated and confined environment, as well as a microgravity environment, on cerebral circulation. However, no studies on cerebral circulation in an isolated and confined environment have been reported. Therefore, we investigated the effects of a 14-day period of confinement in an isolated environment on dynamic cerebral autoregulation. METHODS: We participated in an isolation and confinement experiment conducted by the Japan Aerospace Exploration Agency in 2016. Eight healthy males were isolated and confined in a facility for 14 days. Data were collected on the days immediately before and after confinement. Arterial blood pressure waveforms were obtained using a finger blood pressure monitor, and cerebral blood flow velocity waveforms in the middle cerebral artery were obtained using transcranial Doppler ultrasonography for 6 min during quiet rest in a supine position. Dynamic cerebral autoregulation was evaluated by transfer function analysis between spontaneous variability of beat-to-beat mean arterial blood pressure and mean cerebral blood flow velocity. RESULTS: Transfer function gain in the low- and high-frequency ranges increased significantly (0.54 ± 0.07 to 0.69 ± 0.09 cm/s/mmHg and 0.80 ± 0.05 to 0.92 ± 0.09 cm/s/mmHg, respectively) after the confinement. CONCLUSION: The increases observed in transfer function gain may be interpreted as indicating less suppressive capability against transmission from arterial blood pressure oscillation to cerebral blood flow velocity fluctuation. These results suggest that confinement in an isolated environment for 14 days may impair dynamic cerebral autoregulation. TRIAL REGISTRATION UMIN000020703 , Registered 2016/01/22.
Adult ; Cerebrovascular Circulation ; physiology ; Confined Spaces ; Homeostasis ; physiology ; Humans ; Male ; Middle Aged ; Space Flight ; Young Adult